1. Technical Field
The present invention relates to a display device, more particularly, to a multiple-channel video image display device capable of displaying a plurality of video images, which are received via a plurality of channels, on a single screen.
2. Related Art
Display devices such as cathode-ray tube (CRT), liquid crystal display (LCD) or plasma type display monitors are widely used to display video images generally a single video image at a given time. Many contemporary television receivers as disclosed, for example, in U.S. Pat. No. 4,729,028 for Television Receiver With Multipicture Display issued to Micic et al., U.S. Pat. No. 4,855,833 for Television Channel Selection Apparatus Employing Multi-Picture Display issued to Kageyama et al., U.S. Pat. No. 4,984,082 for Circuit For Displaying Picture Of Multiple Channels issued to Okamura, U.S. Pat. No. 5,045,946 for Method For Multi-Screen Operation In A Picture-In-Picture System issued to Yu, U.S. Pat. No. 5,065,230 for Video Signal Processor For Simultaneously Reproducing A Plurality Of Video Information On A Single Monitor Picture Tube issued to Kumano et al., U.S. Pat. No. 5,093,726 for Multi-Type Multi-Channel Selector issued to Chun, U.S. Pat. No. 5,161,012 for Multi-Screen Generation Circuit issued to Choi, U.S. Pat. No. 5,262,866 for Method For Displaying A Plurality Of Sequential Video Images In A Multi-Screen Picture issued to Hong, U.S. Pat. No. 5,365,278 for Side By Side Television Receiver issued to Willis, U.S. Pat. No. 5,537,152 for Television Receiver For Displaying Registered Broadcast Channels In Display Segments And A Channel Selector Having Similar Segments issued to Ishikawa, and U.S. Pat. No. 5,576,769 for Automatic Synchronization Switch For Side-By-Side Displays issued to Lendaro, are now equipped with picture-in-picture features capable of providing a visual display of a plurality of video images on a screen.
Recent advances in multimedia technology also allow more than one or multiple video images from different video sources to be simultaneously displayed on a single display device of a computer system. Such multiple video images are typically displayed in separated windows on the display device. Generally, synchronization frequencies of different images must be identical, and video signals of different images must be selected for a simultaneous display on the display device. If the synchronization frequencies of the selected images to be displayed on the display device are slightly different from each other, the visual display of multiple images on the display device is corrupted. For this reason, further advance in the image selection and synchronization is necessary to ensure that multiple images are reliably displayed on the display device.